Variable clearance pocket for compressors



May 3, 1932. c. EQBLANK 1,856,460

VARIABLE CLEARANCE POCKET FOR COMPRESSORS Filed Sept. 10, 1930 IN V EN TOR.

BY I f H15 A TTORNEY.

67107 6515127 ism/2 Patented May 3, 1932 7 UNITED STATES PATENT ()FFICE CHARLES E. BLANK, OF PAINTED POST, NEW YORK, ASSIGNOR TO INGERSOLL-RAND COMPANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY VARIABLE CLEARANCE POCKET FOE COMPRESSORS Application fi1ed September 10, 1930. Serial No. 480,905.

This invention relates to improvements in clearance pockets for blowing engines, compressors and the like and more especially to that type whose efi'ective size may be varied to meet the exigencies of operating conditions.

My pocket is of very simple construction and may easily be incorporated in the design of any engine, compressor or the like to which such a pocket is adapted.

Pumps or compressors used as part of a permanent installation as in power houses, refrigerating plants, mines, oil refineries and the like are very often directly connected to a source of steady power, such as a synchronous electric motor, which maintains a constant speed and which is not readily adapted to operate at varying speeds. As the consumption of pressure fluid is variable it is desirable to be able to change the capacity of the compressor. In installations where a constant speed driving unit is employed it is impractical to adopt the ordinary means of changing the velocity of the piston. or of shortening or lengtheningits stroke. By providing a variable clearance pocket for the cylinder in which the piston works, however, the effect of a shortened stroke may be obtained by increasing the size of the pocket and the effect of a lengthened stroke may be obtained by diminishing the size of the pocket.

My object is to provide a clearance pocket at once simple, strong, compact and inexpensive, the effective size of which may be readily, quickly and positively changed.

In that form of my invention illustrated in the accompanying drawings Figure 1 shows a compressor in which my invention has been embodied. The essential parts of the compressor and of the clearance chamber are shown in section.

Figure 2 is an end View of the closure assembly of one end of the clearance pocket taken on the line 22 of Figure 1 looking in the direction of the arrows.

In the drawings in which similar reference characters denote similar parts a compressor is designated generally by A. In the compressor a piston 5 is reciprocated in a cylindrical bore 6 by means of a driving member or rod 7. The piston 5 may have an extension 8 which may be utilized as a piston in another cylinder (not shown) as in a multiple stage compressor.

On both sides of the cylinder and connected thereto by valves (not shown) are fluid chambers 9. In the present illustration the lower chamber may be a low pressure chamber and the upper one a high pressure chamber. In the wall of the high pressure chamber and also about the head of the cylinder are passages or jackets 10 in which cooling water may be circulated.

A cylinder head 14;, through which passes the rod 7, is held in the cylinder by any suitable means. The rod 7 is journaled therein and suitable packing 11, held in place by a packing gland 12, serves to prevent, or at least InlHl7n1lZ8 leakage of pressure fluid along the rod At its inner end the cylinder head 14 is cut away on one side to form a recess 6a which is connected to a clearance pocket 16 by means of a passageway 15 in the cylinder wall and 7 opening into the clearance pocket at a point spaced somewhat from the end of said pocket.

The clearance pocket 16 is part of the bore of a cylinder 17 which may be in the same casting as the bore 6 and is arranged in paralg lelism with respect thereto. A plate 21 fits into and over one end of the bore 17 and forms a closure therefor. It may be retained in place by any suitable means (not shown).

A piston 18 having piston rings 19 is diss5 posed in the bore 17 and is attached to a threaded piston rod 20. The rings 19 are preferably arranged near the inner end of the piston so that the outer or right hand end of the piston may pass readily over the end of the passage 15 for which it acts as a closure during the time the compressor is operatingat full load.

The piston rod extends through a hole in a block 22 which forms the closure for the other end of the bore 16. The hole in the block 22 through which the threaded piston rod extends is slotted to receive a key 27 which engages a groove 26 in one side of the piston rod 20 thereby holding the piston rod,

and of course the piston 18, against rotation.

In threaded engagement with the free end of the piston'rod isa tubular member or hollow shaft 28 one end of which fits into a recess in the head of the block 22 and is held therein by a retaining plate .23 which may be held in place by bolts 32. It is understood thatthe shaft 28 is free to rotate.

Surrounding the tubular member 28 and v enclosed by the retaining plate 23 are packing rings 24 which are held in place by a" packing gland 25.

The other end of the tubular member is supported in an arm 31 which in turn is bolted to the'compressor A. A hand wheel 29 may be attached by means of a bolt 30 to the tubular member 28 to aiford a means for rotating it.-

In practice the clearance pocket is enlarged or diminished by rotating the shaft 28. As the shaft 28 is in threaded engagement with the piston rod 20 and as the latter is prevented from rotating by the key 27 and as the shaft'28 is held against longitudinal motion the action of turning the shaft in one direction serves to draw the piston rod into its interior thereby enlarging the clearance pocket and turning the shaft 28 in the opposite direction serves to expel the piston rod 26 from the interior of the tube and diminish the size of the clearancepocket.

I claim:

1. In combination with a cylinder having a reciprocating piston, a cylinder-head having a recess therein, a cylindrical clearance chamber, a passage in the cylinder connecting the clearance chamber to the recess: in the cylinder head, a piston in the clearance champiston rod rotatable to cause longitudinal mo chamber to the recess in the cylinder head, a

piston "in the clearanceohamber adapted to overlie the passage to form a closure therefor, a threaded pistonrod affixed to the clearance chamber piston, means to hold the threaded piston rod against rotation, and a tubular member in threaded connection With the threaded piston rod rotatable to cause longitudinal motion of the piston within the clearance chamber.

4. In combination with a cylinderhaving reciprocating piston therein, a chamber arranged in parallelism with the cylinder, a passage connecting the chamber and the cylinder and opening into the side of the chamber, a piston slidable in said chamber andbeing adapted to overlie-thepassage to form a closure therefor, and manually operable means to adjust the position of the latter piston in said chamber." a v In testimony whereof I have signed this specification. v

CHARLES E. BLANK.

her, a threaded piston rod affixed to the clearance chamber piston, said piston rod having a longitudinal slot, closures for both ends of the clearance chamber, the closure for one end having a hole to permit the threaded piston rod to pass therethrough, said hole having a slot to receive a key to engage the slot in the threaded piston rod, and a tubular member closed at one end in threaded engagementvwith the piston rod at its other end, said tubular member being rotatable to cause longitudinal movement of the threaded pisjgon rod and the piston in the clearance chamer. V

2. In combination with a cylinder having a reciprocating piston, a cylinder head having a recess therein, a cylindrical clearance chamber, a passage connecting. the clearance chamber to the recess in the cylinder head, a piston in the clearance chamber to overlie the passage for closing saidpassage, a threaded piston rod affixed t0 the clearance chamber piston and extending outside the clearance chamber, means to hold the threaded piston rod against rotation, and a tubular member in threaded connection with the threaded 

